This invention relates to a new and improved control system for adjusting the amount of intravenous solution supplied to a patient based on the rate of weight change of a free hanging load of the solution. A close control of solution feeding rate can be thereby achieved.
As intravenous therapy becomes an increasingly important aspect of patient care, it is important that for many procedures, flow rates must be precisely and safely maintained. Intravenous solutions and additive programs have become more complex, with greater variances in the types of solutions and drugs being administered through intravenous equipment. Fluid balance maintenance is required for many pos-operative patients, pediatric patients, obstetric patients, mental patients, cancer patients, burned patients, and patients with traumatic injuries. In addition, total parenteral nutrition is rapidly gaining momentum, and the administration of nutrients is a prime indication for the use of controlled infusions as are the administration of antibiotics, anticoagulants, electrolytes, labor inducing drugs, and others.
Various feed control systems for intravenous devices are known, and most include a drop counting method. However, these devices are sensitive to variations in drop size caused by temperature and viscosity, drop rate and manufacturing inaccuracy of the drop platform. Another type of I.V. flow control device utilizes a positive displacement, speed controlled pump, but this requires an accurate tolerance of pump components, which is expensive. Usually, commercial intravenous control devices presently claim an accuracy of about 2%-5% for pumps, and a 1%-2% drop rate accuracy for controllers, and both types are fairly expensive.
There is desired a relatively low cost intravenous control device providing constant and precise flow rates. The device should be immune to changes in temperature and viscosity and flow rate as they affect drop size, and should not require disposable components made to a close tolerance. The device should prevent dry and runaway I.V.s.